This invention relates to a system for feeding an original to be duplicated.
One type of original feeding system comprising a rotary drum rotably mounted for attaching an original in sheet form to its periphery, means for driving the rotary drum, and clamping means including claws for clamping the leading edge of the original in sheet form to the periphery of the rotary drum is known, from Japanese Patent Publication No. Sho-41-4426. In this original feeding system, an original in sheet form is attached to the rotary drum during rotation of the latter, and occurrence of mistakes in clamping the original to the rotary drum is inevitable. Other disadvantages of this system are that it is only during rotation of the drum that an original can be fed and that limitations are placed on the length of the original that can be handled by the circumferential length of the rotary drum.
Proposals have been made to provide means for feeding an original to the rotary drum so that the movement of the original is temporarily stopped and the original is clamped to the drum by feeding it at a rate higher than the peripheral velocity of the drum, as in Japanese Patent Publication No. Sho-49-48138. The original feeding system incorporating therein the means described hereinabove has the disadvantage that difficulties are encountered in accurately feeding a sheet original when feeding rates are changed in producing duplicates by varying the duplication mode from one copy size to another, in addition to the disadvantages of the first-mentioned system.
Meanwhile, it is also proposed, as in Japanese Patent Application No. Sho-52-124035, to provide the original feeding system with rotary drum control means for stopping the rotary drum so that the original clamping claws are located in the original feeding position, and means for preventing the original from being released from the original clamping claws when copying is carried out in a repeat copying mode. The original feeding system provided with these means is capable of feeding originals of an endless web type or of a large length. However, when the system handles a sheet original of a large length, there arises the problem that since the sheet original of the large length is fed to the rotary drum while the latter is temporarily rendered stationary, irregularities may occur in feeding originals by temporarily stopping the rotation of the drum and the copies produced may bear the brunt of such irregularities.